Question 15 ?

Question

399 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-03-06T12:17:00

Option C

for this we need the cosine rule

#a^2=b^2+c^2-2bc CosA#

from the question

#5^2=2^2+4^2-(2xx4xx2xxCostheta)#

#25=4+16-16costheta#

solving for #theta#

#(25-20)=-16costheta#

#costheta=-5/16#

#theta=cos^(-1)(-5/16)#

#theta=108.209..^0#

#theta=108^0# to the nearest degree.
So option C is the one required